I changed the plugs in my 2007 F150 5.4 L with 65k miles. All 8 plugs came out great with no brakeage. So i thought everything was good. I put the new plugs (E3 plugs E3.70) in... had a lit of trouble with the far cylinder on the passenger side but eventually got it. Put the coil plugs back on and everything.

Now it idles really rough, shaking the truck, i can hear a "POW" every couple of beats out of the tail pipe ( not really loud) and it hesitates on acceleration.


Any ideas of where to start looking. Please help... we have a trip scheduled in 2 days.

 

Put ford motorcraft plugs back in!! I had same problem then changed them out for the motorcraft plugs and it ran like a champ

 

how was it running before.only thing i can think of is pull the e3s and go with the motorcrafts. is the cel on.

 

You tried the E3 plugs? Everyone else talks highly of them... have you seen the E3 spark plug thread?

https://www.f150online.com/forums/ot...ark-plugs.html

 

No light yet... it had a random bucking before and at 65k everyone was telling me to change plugs.

 

My truck ran ok, I figured I change them just for maintenance put the E3 in it ran rough. Went to advance auto parts they carry the updated plugs (motorcraft).I tried looking to see if one of the E3 plugs were cracked but I couldn't tell. Truck runs alot better. Ur description is exactly what happened to me. Take them out and inspect them for a crack. Good luck let me know what happens

 

Where was the crack? In the porcelain? I wish I knew what cylinder.

 

On the middle of the plug, even if ur CEL is not on check it anyways u might have a pending code

 

U did say ur truck ran good before u changed plugs rite??

 

I had a lot of trouble with the far back cyl on passenger side. I had to use multiple extensions and knuckles and they kept binding. Maybe It felt tight and it really was not tight. I just read that it is ok to remove the computer and bracket. So will remove those and redo that cylinder and see if that fixes it.


Is it possible that if a spark plug is not quite tight enough it will cause this issue? I am just trying to go back through everything i did. That is the only cylinder that gave me any kind of trouble.

 

It had a buck/misfire under load at low rpm ( common with wornout plugs). As far as idle, it was idling amazing. Did not even know the truck was running it was so smooth.

 

Yes it's ok to remove computer and bracket to get to cyl 3 and 4 u will not cause any harm. Check the plugs for a crack it would look like a dark hairline crack. If they look good I still recommend putting motorcraft plugs in ur truck. Let me know what happens

 

Double check all the connectors on the coils just to double check

 

Did you grease the cops when you put them back in? Did you maybe overgrease them and get grease on the contact spring?

 

You arnte supposed to get grease on the contact spring? Dialectric grease does not interfer with electric signals.


I removed computer and was able to get another turn or two out of the #4 spark plug. Started it up and it runs like a champ so far. I am letting the computer reset now and will go for a test drive in a minute.